There is known a 3D display apparatus which can separately project a right video and a left video having disparity therebetween to the right eye and the left eye of a viewer.
A 3D display apparatus provides a three-dimensional view by causing a shift of a display position of a left-eye video and a display position of a right-eye video on the 3D display apparatus in a parallel direction. A left-eye video is shown to the left eye, while a right-eye video is shown to the right eye. If this shift (hereinafter referred to as a disparity amount) is over an appropriate range, the viewer cannot view the three-dimensional video normally. Accordingly, when generating a 3D video, the 3D display apparatus generates a left-eye video and a right-eye video in a manner that the disparity amount converges in a predetermined range.
Here, when a part of video out of the 3D video (hereinafter also referred to as a partial video) is to be enlarged, a disparity of the partial video is enlarged, which makes it impossible for the viewer to view the video normally after enlargement. In order to avoid such a problem, Patent Literature (PTL) 1 discloses a method for allowing a viewer to continuously view the three-dimensional video normally, by changing a magnification according to the disparity amount in the enlargement area.